Gas turbine engines including channel-cooled hooks for retaining a part relative to an engine casing structure

ABSTRACT

A gas turbine engine is provided. The gas turbine engine includes an engine casing structure and a part retained relative to the engine casing structure by a channel-cooled hook. The channel-cooled hook includes at least a portion of a hook cooling channel. A vane assembly for the gas turbine engine is also provided.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of, and claims priority to, U.S.application Ser. No. 14/807,703, filed Jul. 23, 2015 and entitled, “GasTurbine Engines Including Channel-Cooled Hooks for Retaining a PartRelative to an Engine Casing Structure.” The '703 application is herebyincorporated by reference in its entirety.

GOVERNMENT LICENSE RIGHTS

This invention was made with government support underFA-8650-09-D-2923-0021 awarded by the United States Air Force. Thegovernment has certain rights in the disclosure.

FIELD

The present disclosure relates to gas turbine engines, and morespecifically, to gas turbine engines including channel-cooled hooks forretaining a part relative to an engine casing structure.

BACKGROUND

Gas turbine engines typically include at least a compressor section, acombustor section and a turbine section. During operation, air ispressurized in the compressor section and is mixed with fuel and burnedin the combustor section to generate hot combustion gases. The hotcombustion gases are communicated through the turbine section whichextracts energy from the hot combustion gases to power the compressorsection and other gas turbine engine loads. One or more sections of thegas turbine engine may include a plurality of vane assemblies havingvanes interspersed between rotor assemblies that carry the blades ofsuccessive stages of the section. The rotor assemblies may be disposedradially inward of an annular blade outer air seal (BOAS).

SUMMARY

A gas turbine engine is provided in accordance with various embodiments.The gas turbine engine includes an engine casing structure and a partretained relative to the engine casing structure by a channel-cooledhook. The channel-cooled hook includes at least a portion of a hookcooling channel.

A gas turbine engine is provided in accordance with various embodiments.The gas turbine engine comprises an engine casing structure including acase hook and a part having a hook and retained relative to the enginecasing structure by the hook mating with the case hook. At least one ofthe hook and the case hook include at least a portion of a hook coolingchannel defining a channel-cooled hook.

A vane assembly is provided for a gas turbine engine in accordance withvarious embodiments. The vane assembly comprises a vane having a vanehook of a pair of vane hooks configured to be received by a case hook ofan engine casing structure. At least one of the vane hook and the casehook including at least a portion of a hook cooling channel to define achannel-cooled hook. A dam extends from and between the pair of vanehooks to prevent the flow of a cooling fluid between the pair of vanehooks and directs the cooling fluid into and through the hook coolingchannel.

In any of the foregoing embodiments, the part comprises a vane retainedrelative to the engine casing structure by the channel-cooled hookcomprising a vane hook. The dam comprises at least one of anon-segmented rail or a feather seal extending between the pair ofhooks. The part comprises a blade outer air seal (BOAS) retained to theengine casing structure by the channel-cooled hook comprising a BOAShook. The channel-cooled hook comprises a segmented, L-shaped hook. Thehook cooling channel includes heat transfer enhancement featuresincluding at least one of rib turbulators, pin fins, or pedestals. Thehook cooling channel comprises a bore extending through thechannel-cooled hook. The portion of the hook cooling channel cooperateswith a coverplate mounted over the portion to define the hook coolingchannel.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will hereinafter be described in conjunction withthe following drawing figures, wherein like numerals denote likeelements, and wherein:

FIG. 1 illustrates a conventional gas turbine engine;

FIG. 2 illustrates a conventional flow scheme through a portion of aturbine section of the conventional gas turbine engine of FIG. 1;

FIG. 3 is similar to FIG. 2, illustrating a flow scheme through aportion of the turbine section of a gas turbine engine according tovarious embodiments;

FIG. 4 is an isometric view of a vane segment, illustrating hook coolingchannels of the vane hooks containing various heat transfer enhancementfeatures;

FIG. 5 illustrates a pair of the vane segments of FIG. 4 with a firstfeather seal between the vane segments and a dam comprising a firstnon-segmented rail and a second non-segmented rail from and between,respectively, the vane hooks at the leading edge and the vane hooks atthe trailing edge; and

FIG. 6 illustrates a pair of vane segments with a feather seal betweenthe vane segments and a dam comprising feather seals from and between,respectively, the vane hooks at the leading edge and the vane hooks atthe trailing edge and a hook cooling channel formed by a coverplateoverlying the vane hook.

The subject matter of the present disclosure is particularly pointed outand distinctly claimed in the concluding portion of the specification. Amore complete understanding of the present disclosure, however. may bestbe obtained by referring to the detailed description and claims whenconsidered in connection with the drawing figures, wherein like numeralsdenote like elements.

DETAILED DESCRIPTION

The detailed description of exemplary embodiments herein makes referenceto the accompanying drawings, which show exemplary embodiments by way ofillustration. While these exemplary embodiments are described insufficient detail to enable those skilled in the art to practice theinventions, it should be understood that other embodiments may berealized and that logical changes and adaptations in design andconstruction may be made in accordance with this invention and theteachings herein. Thus, the detailed description herein is presented forpurposes of illustration only and not of limitation. The scope of theinvention is defined by the appended claims. For example, the stepsrecited in any of the method or process descriptions may be executed inany order and are not necessarily limited to the order presented.Furthermore, any reference to singular includes plural embodiments, andany reference to more than one component or step may include a singularembodiment or step. Also, any reference to attached, fixed, connected orthe like may include permanent, removable, temporary, partial, fulland/or any other possible attachment option. Additionally, any referenceto without contact (or similar phrases) may also include reduced contactor minimal contact. Furthermore, any reference to singular includesplural embodiments, and any reference to more than one component or stepmay include a singular embodiment or step.

Various embodiments are directed to gas turbine engines includingchannel-cooled hooks for retaining a part relative to an engine casingstructure. As used herein, the term “channel-cooled hooks” may refer tohooks for retaining a part relative to the engine casing structure andthat include at least a portion of a hook cooling channel according tovarious embodiments. Without a hook cooling channel included in thehooks, hook temperatures may exceed hook material temperaturecapability, thereby lowering hook strength and hook retentioncapabilities. Even if temperature capabilities are not exceeded, lowerhook temperatures are able to be maintained, resulting in lowerstresses, permitting thinner hooks and saving overall weight.Additionally, gas turbine engine structures surrounding thechannel-cooled hooks may benefit from lower temperatures enabled by thechannel-cooled hooks.

As used herein, a “part” that may be retained relative to an enginecasing structure with one or more channel-cooled hooks includes a bladeouter air seal (BOAS), a vane, a combustor, and the like. Thechannel-cooled hooks may be BOAS hooks, vane hooks, case hooks, andother hooks (all collectively referred to as “hooks” or a “hook”, unlessspecified otherwise) used for retaining a part relative to the enginecasing structure.

FIG. 1 schematically illustrates a conventional gas turbine engine 10.The exemplary gas turbine engine 10 is a two spool turbofan engine thatgenerally incorporates a fan section 14, a compressor section 16, acombustor section 18 and a turbine section 20. Alternative engines mightinclude fewer or additional sections such as an augmenter section (notshown), among other systems or features. Generally, the fan section 14drives air along a bypass flow path, while the compressor section 16drives air along a core flow path for compression and communication intothe combustor section 18. The hot combustion gases generated in thecombustor section 18 are expanded through the turbine section 20. Thisview is highly schematic and is included to provide a basicunderstanding of the gas turbine engine 10 and not to limit thedisclosure. This disclosure extends to all types of gas turbine enginesand to all types of applications. including but not limited to, threespool turbofan configurations. The gas turbine engine 10 generallyincludes at least a low speed spool 22 and a high speed spool 24 mountedfor rotation about an engine centerline axis 12 relative to an engineease 27 via several bearing systems 29. The low speed spool 22 generallyincludes an inner shaft 31 that interconnects a fan 33, a low pressurecompressor 17, and a low pressure turbine 21. The inner shaft 31 canconnect to the fan 33 through a geared architecture 35 to drive the fan33 at a lower speed than the low speed spool 22. Although the gearedarchitecture 35 is schematically depicted between the fan 33 and the lowpressure compressor 17, it should be understood that the gearedarchitecture 35 could be disposed at any location of the gas turbineengine, including but not limited to, adjacent the low pressure turbine21. The high speed spool 24 includes an outer shaft 37 thatinterconnects a high pressure compressor 19 and a high pressure turbine23.

A combustor 15 is arranged between the high pressure compressor 19 andthe high pressure turbine 23. The inner shaft 31 and the outer shaft 37are concentric and rotate about the engine centerline axis 12. A coreairflow is compressed by the low pressure compressor 17 and the highpressure compressor 19, is mixed with fuel and burned within thecombustor 15, and is then expanded over the high pressure turbine 23 andthe low pressure turbine 21. The turbines 21, 23 rotationally drive thelow speed spool 22 and the high speed spool 24 in response to theexpansion.

The compressor section 16 and the turbine section 20 can each includealternating rows of rotor assemblies 39 and vane assemblies 41. Therotor assemblies 39 carry a plurality of rotating blades 43, while eachvane assembly 41 includes a plurality of vanes 45 (FIG. 2). The rotatingblades 43 of the rotor assemblies 39 create or extract energy (in theform of pressure) from the airflow that is communicated through the gasturbine engine 10. The vanes 45 of the vane assemblies 41 direct airflowto the blades of the rotor assemblies 39 to either add or extractenergy. Each vane of the vane assemblies 41 is circumferentiallyretained to the engine as hereinafter described.

FIG. 2 illustrates a turbine portion 100 of the gas turbine engine 10.FIG. 3 illustrates a turbine portion 100 of a gas turbine engine 500according to various embodiments. The turbine portion 100 of gas turbineengine 500 includes a vane assembly 410 according to various embodimentsas hereinafter described. This disclosure is not limited to the turbinesection 20, and could extend to other sections of the gas turbine engine10, including but not limited to the compressor section 16. As notedpreviously, the turbine section 20 can include alternating rows of rotorassemblies 39 and vane assemblies 41. The rotor assemblies 39 may bedisposed radially inward of an annular blade outer air seal (BOAS) 47.The BOAS 47 is disposed at an outer diameter of a tip of the blade(s) 43and provides an outer diameter flow path for the core airflow. A vaneinner platform 51 provides an inner diameter flow path for the coreairflow.

Each vane assembly 41 includes the plurality of vanes 45 that arecircumferentially disposed (into and out the page of FIG. 2) about theengine centerline axis 12 (FIG. 1). Each vane 45 includes an airfoil 49that extends between a vane inner platform 51 and a vane outer platform53. Hot combustion gas flows between vane inner platform 51 and the vaneouter platform 53. The vanes 45 may be configured to provide a singleairfoil or may be arranged in vane segments (e.g., FIG. 5) of multipleairfoils. The vane 45 may be a stationary vane or a variable vane andcould be cantilevered. The vane 45 includes the airfoil 49, an inner end57 at an inner diameter, and an outer end 59 at the outer diameter. Theairfoil 49 comprises a leading edge 61, a trailing edge 63, a pressureside 65 and a suction side 67 (FIG. 4).

The vane assembly 41 is connected to an engine casing structure 69associated with the portion 100 of the gas turbine engine 10. The enginecasing structure 69 includes at least one case hook 71, for purposes ashereinafter described. The case hook 71 may be segmented (i.e., does notspan a full circumference). The BOAS 47 and the vane assemblies 41 maybe disposed radially inward of the engine casing structure 69. One orboth of the BOAS 47 and vane assemblies 41 may be segmented and includea feather seal 11 between segments to help prevent leakage of coolingfluid between the segments as hereinafter described.

Still referring to FIGS. 2 and 3, the BOAS 47 and the vanes 45 of theturbine section 20 are retained to the engine casing structure 69 byBOAS hooks 73 of the BOAS and vane hooks 75, respectively. The vanehooks 75 are used to achieve radial and axial attachment of the vanerelative to the engine casing structure 69. The BOAS hooks 73 and vanehooks 75 are mated with and received by the case hooks 71 of the enginecasing structure 69. A plurality of BOAS hooks 73 and vane hooks 75respectively retain the BOAS 47 and the vanes 45 to the engine casingstructure 69 for proper functioning during gas turbine engine operation.

As hereinafter described, in accordance with various embodiments, andwith specific reference to FIG. 3, at least one of the case hook, theBOAS hook, or the vane hook may comprise a channel-cooled hook eachincluding at least a portion of a hook cooling channel. A case hookincluding at least a portion of a hook cooling channel is referred to inFIG. 3 with reference numeral 171. A BOAS hook including at least aportion of a hook cooling channel is referred to in FIG. 3 withreference numeral 173 while the vane hook including at least a portionof a hook cooling channel is referred to in FIG. 3 with referencenumeral 175. The hook cooling channel in the case hook, the BOAS hook,and the vane hook is referred to in FIG. 3 with reference numeral 176.

The conventional flow scheme through the turbine section is depicted inFIG. 2. Cooling fluid indicated by arrows A, such as bleed air, isintroduced into an inner diameter vane cavity 77 through an orifice 79and may also be introduced to the vane through a turbine cooling fluid(TCA) pipe 81 at the outer diameter of the vane. The turbine coolingfluid (TCA) pipe 81 at the outer diameter of the vane introduces coolingfluid (arrows A) to the vane. The cooling fluid also mixes with coolingfluid from an upstream source. Cooling fluid may be provided to the vaneand the airfoil 49 through a serpentine cooling circuit 83 (FIG. 2).Cooling fluid flows aft across the BOAS 47 and past a first set of BOAShooks 73. The cooling fluid continues on past a leading edge/forwardvane hook 75, mixes with the cooling fluid introduced by the TCA pipe81, and continues traveling aft past the trailing edge/aft vane hook 75,then flowing across the aft BOAS 47 and past the second set of BOAShooks 73. As the cooling fluid flows aft, a portion of the cooling fluidleaks out (becoming leakage fluid) across the feather seal 11 betweenvane segments as depicted in FIG. 2 by arrows B, and between the BOASand an adjacent vane as depicted in FIG. 2 by arrows C.

FIG. 3, in accordance with various embodiments, illustrates a flowscheme through the turbine section of the gas turbine engine 500according to various embodiments. The vane assembly 410 according tovarious embodiments comprises a vane having a vane hook configured to bereceived by a case hook of an engine casing structure, at least one ofthe vane hook and the case hook including a hook cooling channeldefining a channel-cooled hook and a dam extending from and between apair of the hooks (more particularly, vane hooks in the depictedembodiment) to prevent the flow of a cooling fluid between hooks anddirecting the cooling fluid into and through the hook cooling channel ashereinafter described.

As noted previously, case hooks 171, BOAS hooks 173, and vane hooks 175are depicted as including at least a portion of a hook cooling channel176 each forming a channel-cooled hook. It is to be understood that,fewer than all the hooks may include at least a portion of the hookcooling channel and that channel-cooled hooks may be in a sequence otherthan that depicted in FIG. 3. In various embodiments, the channel-cooledhooks may be segmented (i.e., does not span a full circumference),having a generally L-shape. The segmented hooks do not span across theentire circumference of the part (i.e., in and out the page of FIG. 3).

Still referring to FIG. 3. according to various embodiments, the Mowscheme through the gas turbine engine according to various embodimentsis described below and is similar to the conventional flow schemepreviously described, with the exceptions as noted below. During engineoperation, cooling fluid, such as bleed air, is introduced into an innerdiameter vane cavity through an orifice and may also be introduced tothe vane through a turbine cooling fluid (TCA) pipe 81 at the outerdiameter of the vane. The turbine cooling fluid (TCA) pipe at the outerdiameter of the vane introduces cooling fluid to the vane. The coolingfluid also mixes with cooling fluid from an upstream source. Coolingfluid may be provided to the vane and the airfoil itself through aserpentine cooling circuit. Cooling fluid flows aft across the BOAS,into the hook cooling channel 176 (if present) of the BOAS hooks 173,and past a first set of BOAS hooks. The cooling fluid continues on pasta leading edge/forward vane hook, mixes with the cooling fluidintroduced by the TCA pipe, and continues traveling aft past thetrailing edge/aft hook flowing across the BOAS and past the second setof BOAS hooks. The cooling fluid may also flow through a hook coolingchannel 176 (if present) in a case hook 171. A seal 190 positioned asshown in FIG. 3 may be used to prevent aft flow through the seal anddirect the cooling fluid toward the hook cooling channel. The seal 190may be a retaining ring seal, a dogbone seal, or other full hoop seal orthe like. The seal 190 may rest against an axial stop 191 in asurrounding component (a BOAS 47 and/or vane 45) to prevent the seal 190from moving aft.

As noted previously, a portion of the cooling fluid may leak across thefirst feather seal between vane segments (arrows B) and between the BOASand an adjacent vane (arrows C). The cooling fluid is directed to andthrough the hook cooling channels of the channel-cooled hooks by the damas hereinafter described in accordance with various embodiments,resulting in higher heat transfer of the hooks relative to hooks withouthook cooling channels. The hook cooling channels have a much smallerflowpath area than the gap D between the circumferentially adjacenthooks (FIGS. 4 and 5), thereby improving heat transfer of the hooks.

The hook cooling channel may be formed in the hook by a number ofmanufacturing methods. For example, in various embodiments, the hookcooling channel comprises a bore extending through the hook, the hookcooling channel comprising the bore integrally formed in the vane hookby casting (using, for example, a ceramic core or refractory metal coreto form the hook cooling channel therein), machining, additivemanufacturing such as direct metal laser sintering (DMLS), or the like.The bore comprises a tubular enclosed passage. In various embodiments,the channel-cooled hook comprises a hook on which a coverplate 90 (FIGS.5 and 6) may be mounted over the portion of the hook, thereby definingthe hook cooling channel 176 disposed between the portion of the hookand the coverplate. The portion of the hook over which the coverplate ismounted or otherwise disposed has an open side that is covered by thecoverplate. The coverplate 90 may be comprised of sheet metal that maybe welded over the hook. The cover plate may alternatively be cast orotherwise integrally manufactured with the rest of the vane. The hookcooling channel 176 may be formed in the vane hook, BOAS hook, the casehook, etc. using the same methods.

Referring now to FIG. 4, according to various embodiments, the interiorsurface of the hook cooling channel may be substantially smooth or mayinclude heat transfer enhancement features such as rib turbulators (alsoknown as “trip strips”) 200 a, pedestals or pin fins 200 b. or the like.Substantially smooth hook cooling channels have the least amount ofpressure drop, but also tend to have a lower heat transfer coefficient.The heat transfer enhancement features turbulate the flow increasing theheat transfer coefficient, but also causing a pressure drop. If there isno pressure drop (i.e., no pressure difference in the cooling fluidbetween the leading edge of the hook and the trailing edge of the hook),the cooling fluid may not flow through the hook. Therefore, thepresence, type, and/or absence of heat transfer enhancement features isa balance between the pressure drop between the leading and trailingedges of the hooks and the desired heat transfer coefficient.

Referring again to FIGS. 5 and 6, according to various embodiments asnoted previously, the gas turbine engine may further comprise the darnto seal the open gap D between circumferentially adjacent hooks (vanehooks in the depicted embodiment). The dam stops the flow betweenadjacent hooks and directs flow toward the hook cooling channels. Invarious embodiments, as depicted in FIG. 5, the dam comprises a firstnon-segmented rail 300 a and a second non-segmented rail 300 b. Thefirst non-segmented rail spans from and between circumferentiallyadjacent vane hooks along the leading edge of the outer platform and thesecond non-segmented 300 b rail spans between circumferentially adjacentvane hooks along the trailing edge of the outer platform. The first andsecond non-segmented rails 300 a and 300 b may be cast with the vaneshaving the vane hooks. In accordance with various embodiments, the firstnon-segmented rail may be integral (one-piece) with thecircumferentially adjacent vane hooks at the leading edge of the outerplatform and the second non-segmented rail may be integral (one-piece)with the circumferentially adjacent vane hooks at the trailing edgeforming, respectively, a non-segmented leading edge vane hook and anon-segmented trailing edge vane hook. As used herein, the term“non-segmented” refers to spanning a full circumference. In order forthe cooling fluid to get past the non-segmented rails and into an aftcavity, the cooling fluid is directed toward and through the hookcooling channels 176 as depicted in FIG. 3.

Referring now specifically to FIG. 6, in accordance with variousembodiments, the dam may comprise a second feather seal 400 disposedbetween circumferentially adjacent hooks. The second feather seal 400may extend in feather seal slots 402 in the outer platform and inopposing sides of the circumferentially adjacent vane hooks. The secondfeather seal 400 may be welded to the outer platform and/or thecircumferentially adjacent vane hooks to prevent the feather seal frombecoming dislodged. The second feather seal may alternatively oradditionally be retained in place by an overlying coverplate (if used toform the hook cooling channel). It is to be understood that acombination of the rail and second feather seal may be used as the dam.Moreover, it is to be understood that a dam as described herein may beused between a pair of BOAS hooks and/or case hooks in the same manneras between a pair of vane hooks.

Various embodiments as described in the present disclosure enable thechannel-cooled hooks to move larger amounts of heat per unit time,thereby maintaining hook strength and hook retention capabilities. Lowertemperatures are able to be maintained during operation, resulting inlower stresses, permitting thinner hooks and saving overall weight.Additionally, structures surrounding the channel-cooled hooks benefitfrom the lower temperatures enabled by the channel-cooled hooks.

Benefits, other advantages, and solutions to problems have beendescribed herein with regard to specific embodiments. Furthermore, theconnecting lines shown in the various figures contained herein areintended to represent exemplary functional relationships and/or physicalcouplings between the various elements. It should be noted that manyalternative or additional functional relationships or physicalconnections may be present in a practical system. However, the benefits,advantages, solutions to problems, and any elements that may cause anybenefit, advantage, or solution to occur or become more pronounced arenot to be construed as critical, required, or essential features orelements of the disclosure. The scope of the disclosure is accordinglyto be limited by nothing other than the appended claims, in whichreference to an element in the singular is not intended to mean “one andonly one” unless explicitly so stated, but rather “one or more.”Moreover, where a phrase similar to “at least one of A, B, or C” is usedin the claims, it is intended that the phrase be interpreted to meanthat A alone may be present in an embodiment, B alone may be present inan embodiment, C alone may be present in an embodiment, or that anycombination of the elements A, B and C may be present in a singleembodiment; for example, A and B, A and C, B and C, or A and B and C.Different cross-hatching is used throughout the figures to denotedifferent parts but not necessarily to denote the same or differentmaterials.

In the detailed description herein, references to “one embodiment”, “anembodiment”, “various embodiments”, etc., indicate that the embodimentdescribed may include a particular feature, structure, orcharacteristic, but every embodiment may not necessarily include theparticular feature, structure, or characteristic. Moreover, such phrasesare not necessarily referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with an embodiment, it is submitted that it is within theknowledge of one skilled in the art to affect such feature, structure,or characteristic in connection with other embodiments whether or notexplicitly described. After reading the description, it will be apparentto one skilled in the relevant art(s) how to implement the disclosure inalternative embodiments.

Furthermore, no element, component, or method step in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element, component, or method step is explicitly recited inthe claims. No claim element herein is to be construed under theprovisions of 35 U.S.C. 112(1) unless the element is expressly recitedusing the phrase “means for.” As used herein, the terms “comprises”,“comprising”, or any other variation thereof, are intended to cover anon-exclusive inclusion, such that a process, method, article, orapparatus that comprises a list of elements does not include only thoseelements but may include other elements not expressly listed or inherentto such process, method, article, or apparatus.

What is claimed is:
 1. A gas turbine engine comprising: an engine casingstructure; and a part retained relative to the engine casing structureby a first hook, wherein the first hook defines, at least a portion of,a first hook cooling channel extending axially through the first hook,wherein the first hook cooling channel comprises a tubular passageenclosed by the first hook.
 2. The gas turbine engine of claim 1,wherein the part comprises a vane, and wherein the first hook comprisesa first vane hook.
 3. The gas turbine engine of claim 2, wherein thevane further comprises a second vane hook, the second vane hookdefining, at least a portion of, a second hook cooling channel extendingaxially through the second vane hook, and wherein the first vane hook islocated proximate a leading edge of the vane and the second vane hook islocated proximate a trailing edge of the vane.
 4. The gas turbine engineof claim 1, wherein the part comprises a blade outer air seal, and thefirst hook comprises a blade outer air seal hook.
 5. The gas turbineengine of claim 1, wherein the first hook comprises a case hookextending from the engine casing structure.
 6. The gas turbine engine ofclaim 1, wherein the part comprises: the first hook; a second hookcircumferentially adjacent to the first hook; and a dam extendingbetween the first hook and the second hook.
 7. The gas turbine engine ofclaim 6, wherein the dam comprises a non-segmented rail formedintegrally with the first hook and the second hook.
 8. The gas turbineengine of claim 6, wherein the dam comprises a feather seal.
 9. The gasturbine engine of claim 1, wherein the first hook cooling channelincludes heat transfer enhancement features including at least one ofrib turbulators, pin fins, or pedestals.
 10. A gas turbine enginecomprising: an engine casing structure including a case hook; and a parthaving a first hook, wherein the part is retained relative to the enginecasing structure by the first hook mating with the case hook, andwherein the first hook defines at least a portion of a first hookcooling channel extending axially through the first hook.
 11. The gasturbine engine of claim 10, wherein the first hook cooling channelcomprises a tubular passage enclosed by the first hook.
 12. The gasturbine engine of claim 10, further comprising a coverplate mounted overthe first hook, wherein the first hook cooling channel is bounded by thefirst hook and the coverplate.
 13. The gas turbine engine of claim 10,wherein the part is a vane and the first hook is a first vane hook. 14.The gas turbine engine of claim 13, wherein the vane further comprises asecond vane hook, the second vane hook defining, at least a portion of,a second hook cooling channel extending axially through the second vanehook, and wherein the first vane hook is located proximate a leadingedge of the vane and the second vane hook is located proximate atrailing edge of the vane.
 15. A vane assembly for a gas turbine engine,the vane assembly comprising: a vane; a forward vane hook locatedproximate a leading edge of the vane and configured to be received by afirst case hook of an engine casing, the forward vane hook defining, atleast a portion of, a first hook cooling channel; and an aft vane hooklocated proximate a trailing edge of the vane and configured to bereceived by a second case hook of the engine casing, the aft vane hookdefining, at least a portion of, a second hook cooling channel.
 16. Thevane assembly of claim 15, wherein the first hook cooling channelextends axially through the forward vane hook, and wherein the secondhook cooling channel extends axially through the aft vane hook.
 17. Thevane assembly of claim 15, wherein the first hook cooling channelcomprises a tubular passage enclosed by the forward vane hook.
 18. Thevane assembly of claim 15, further comprising a coverplate mounted overat least one of the forward vane hook or the aft vane hook.
 19. The vaneassembly of claim 15, further comprising a dam extendingcircumferentially from at least one of the forward vane hook or the aftvane hook.
 20. The vane assembly of claim 19, wherein the dam isconfigured to block an axial flow of air and direct air toward the atleast one of the forward vane hook or the aft vane hook.